Copper alloy amenable to heat treatment



Patented Jan. 26, 1937 PATENT OFFICE corn-2a Armor mm m HEAT TREATMENTUlrich Baydt, Klaus Harmer,

Osnabruck, Germany, assignora to and Max Venzlafl,

Firma snabriicker Kupierund Drahtwerk, Osnabruck Germany, a firm ofGermany No Drawing. Application October 18, 1934, Serial No. 748,965. InGermany October 18, 1933 2 Claims.

It is known to make additions of manganese, cobalt and chromium eitherseparately or several at a time to pure copper or to copper alloys, forexample tin bronzes. Alloys of most varied com- 5 position containingtheseconstituents are used for many diiierent purposes. The saidadditional substances improve the properties of the alloys in variousrespects. The alloys, however, with the exception of copper-chromiumalloys are not amenable to heat treatment. 7 By means of the presentinvention it is possible to make these alloys amenable also to heattreatment and to obtain values for the tensile strength and hardnesswhich far exceed the values for the corresponding hitherto known alloyswhich were not responsive to heat treatment. The alloys are maderesponsive to heat treatment by an addition 01' phosphorus in theproportion of about 0.1% or more in addition to the above mentionedadditions of manganese, cobalt and chromium. The upper limit of thephosphorus content is determined by the capability for being workedwhich the alloys are to 3| Manganese, cobalt and chromium may be presentin the alloy either separately or two or more oil them may be present atthe same time. The total content oi these metals should not be less than0.2%, if the alloy is to be amenable to heat 80 treatment. There is noupper limit to the content of these additional metals in the alloy, and

they may be present in far greater proportions than corresponds to thephosphorus content having regard to the fact that the property of being36 amenable to heat treatment is probably due to the effect of thecorresponding metallic phosphirle, such as for example Walk. The alloyscan also contain tin, zinc and other of the usual constituents of copperalloys. Iron also has an 40 advantageous effect as is otherwise usual.

The new alloys can be heat-treated by heat I ing them to a temperatureabove 700 C., quenching and ageing at 400-600 C. The heat treatment canalso be carried out by heating the 5 alloysto temperatures above 700 andthen gradually cooling them. In this way values are obtained for thetensile strength and hardness of the alloys which exceed the valuesobtained for the quenched alloys but are, in general, less than 5 thevalues obtained when the heat treatment consists of heating, quenchingand ageing. The alloys which have been cooled down slowly can, however,also be tempered in the same manner as the quenched alloys, in whichcase approximately 5 the same values are obtained as for the quenchedand in the tempered pieces.

Cast alloys as well as alloys capable of being formed plastically, forinstance, by rolling or drawing, are amenable to the heat treatment. Thelatter can be subjected after the forming and before the tempering oreven after the heat treatment has been completed, to a subsequent coldtreatment whereby known increases in tensilestrength, hardness etc. areobtained though the elongation is simultaneously reduced.

The improved qualities possessed by the new alloys will be seen from thefollowing comparative figures for the tensile strength, hardness andelongation.

An alloy containing 2% of manganese in the cooled condition had atensile strength 01' about kg./mm. with an elongation of 45% and aBrinell hardness of 61 kg./mm. When this alloy was subjected to heattreatment as above described these figures did not alter in any way.when 0.15% of phosphorus was added to the same alloy, a test samplequenched from 800-900 C. had a tensile strength of 26 kgJmmfi, anelongation of somewhat over 40% and a Brinell hardness of 65-70 kg./mm.'when this alloy was tempered at about 500 C., the tensile strength roseto about 36 kg./mm. and the Brinell hardness to 110-120 kgJmmF, whilethe elongation fell to about 20%. when the quenching process was omittedin the case of this alloy and thealloy was allowed to cool downnaturally from 800-900 C., the value for the tensile strength was aboutkg./mm. when this naturally cooled sample was tempered almost the samefigures were obtained as those indicated. previously for the quenchedand tempered sample. I

In the case of an alloy containing 0.6% manganese and 0.3% phosphorus aswell as 1.8% tin and 0.15% iron and subjected to heat treatment atensile strength of about 45 ken/mm. and a Brinell hardness of 130-140kg./mm. were obtained with an extension 01' about 30%.

What we claim is:-

1'. 'An age hardened copper base alloy, free of beryllium, containingnot less than 0.2% of manganese and from 0.1 to 0.5% phosphoruscharacterized by the fact that the age hardening is due primarily to thecombined effect of the manganese and phosphorous.

2. An age hardened copper base alloy free of beryllium, containing about0.6% manganese, about 0.3% phosphorus, from 1 to 2% tin, and 0.1% to0.2% iron, the remainder being copper.

ULRICH RAYIYI. KLAUS I-IANSE'Et.v MAX VENZLAFF.

